Process for producing diene polymers

ABSTRACT

The invention describes a process for producing a diene polymer, the process including the following steps in this order i) polymerizing one or more diene monomers in the presence of a catalyst composition to give a reaction mixture; ii) adding to the reaction mixture one or more alkoxysilane compounds; iii) adding S2Cl2, SCl2, SOCl2, S2Br2, SOBr2 or a mixture thereof to the reaction mixture; and iv) optionally adding a protic agent to the reaction mixture so as to deactivate the catalyst. The invention further includes polymers that are obtainable according to this process, as well as products including the polymer.

This application claims priority to International Application No.PCT/EP2012/053426 filed Feb. 29, 2012; the entire contents of which isincorporated herein by reference.

The present invention relates to a process for producing diene polymers,in particular modified elastomeric polymers, such as rubber, inparticular high cis polybutadiene, comprising the steps of polymerizingone or more diene monomers in the presence of a catalyst composition togive a reaction mixture followed by the addition of one or morealkoxysilane compounds and the subsequent addition of at least one thiocompound. The present invention further relates to diene polymers thatare obtainable according to the process described herein. In addition,products comprising the diene polymers are described. Products includecured polymers and formulations comprising cured polymers and a filler.

The preparation of polydienes on the basis of Ziegler-Natta catalysts isknown, and corresponding polydienes including high cis polybutadienefind use in many applications, e.g. in tire tread compounds. Commonprocesses yield polymers, such as for example, polybutadiene comprisingcis-1,4-polybutadiene as major polymer fraction in commercial quality.However, such processes are associated with certain drawbacks includingside reactions, including chain transfer reactions duringpolymerization, and the need for additives, e.g. processing aids afterpolymerization, particularly during (reactive mixing) formation ofpolymer-filler compositions. Also processing of the diene-polymers inthe course of the polymer manufacturing process may be impaired. Oftenhigh polymer solution viscosities require reduction of the concentrationof the polymer in solution. Furthermore, polymer properties such as forexample undesired cold flow are observed and processing behavior isoften insufficient.

Prior art attempts to address these problems by means of temperaturecontrol, the use of special catalyst components and addition of sulphurcompounds. These processes, however, either lead to increased energyconsumption during manufacture and conversion, inferior polymerproperties or unpleasant odor. Thus, prior art efforts have beendirected to alternative means. Especially, EP 0 707 017 A1 considers aprocess for producing diene rubbers by polymerization with Nd-catalysts.The process disclosed in this application adiabatically polymerizesdienes at temperatures of −20° C. to 150° C. in the presence of an inertorganic solvent. The process comprises the step of converting thereaction mixture from reduced to atmospheric pressure followed by atreatment with disulfur dichloride, sulfur dichloride or thionylchloride. The results obtained according to

EP 0 707 017 A1 are still not satisfactory. In particular, polymersobtained according to this process still lack beneficial processingbehaviors, and performance properties of products comprising these priorart polymers may also need to be improved.

It is thus an object of the present invention to provide an improvedprocess for producing diene polymers which allows the preparation ofpolymers, in particular rubbers, with favorable processing behavior. Inthis context, a favorable processing behavior refers to an easy and fastmixing of the polymers in, e.g. rubber compound formulations includingfillers. It is a further object of the invention to provide polymerswhich allow the preparation of products, such as tires, having goodperformance properties. Typical performance properties are related tohysteresis properties including tan delta values at 60° C. (aslaboratory rolling resistance indicator), 0° C. (as wet grip indicator)and −10° C. (as ice grip indicator), but may also include abrasion anddynamic modulus. In this regard, it has been observed that linear highmolecular weight diene polymers show a good balance in terms of rollingresistance, wet grip and abrasion resistance in cured rubberformulations comprising filler. Linear high molecular weight dienepolymers, however, are associated with high polymer solution viscositiesas compared to branched polymers of identical weight average molecularweight (Mw). Moreover, once solvent free, these linear polymers are moredifficult to mix with fillers as compared to branched polymers.

Accordingly, there is a further need for polymers combining the positiveaspects of branched and linear polymers. Particularly, it would bedesirable to provide diene polymers with improved solution viscositiesand improved processing characteristics when mixed with fillers without,or without significantly, impacting hysteresis and wear properties ofcured rubber formulations comprising the polymer and the filler.

In a first aspect, the present invention therefore relates to a processfor producing a diene polymer, the process comprising the followingsteps in this order

-   -   i) Polymerizing one or more diene monomers in the presence of a        catalyst composition to give a reaction mixture; wherein the        catalyst composition comprises one or more of a carboxylate, an        alkyl phosphate, an alkyl phosphite, an alcoholate, an amide and        a hydrocarbyl compound of a rare earth element having an atomic        number of 57 to 71 in the periodic table, and at least one        activator compound, or a reaction product of the at least one        activator compound and the carboxylate, alkyl phosphate, alkyl        phosphite, alcoholate, amide and/or hydrocarbyl compound of the        rare earth element;    -   ii) Adding to the reaction mixture one or more alkoxysilane        compounds selected from the compounds represented by the        following formulae (A1), (A2), (A3), (A4) and (A5):        ((R¹O)_(q)(R²)_(r)Si)_(s)  (A1)        -   wherein in formula (A1): Si is silicon and O is oxygen;        -   s is an integer selected from 1 and 2;        -   with the proviso that if s is 1, then q is an integer            selected from 2, 3 and 4; r is an integer selected from 0, 1            and 2; and q+r=4;        -   and if s is 2, then q is an integer selected from 1, 2 and            3; r is an integer selected from        -   0, 1 and 2; and q+r=3;            ((R³O)_(t)(R⁴)_(u)Si)₂O  (A2)        -   wherein in formula (A2): Si and O are as defined above;        -   t is an integer selected from 1, 2 and 3;        -   u is an integer selected from 0, 1 and 2;        -   and t+u=3;            (R⁵O)_(w)(R⁶)_(x)Si—R⁷—S—SiR⁸ ₃  (A3)        -   wherein in formula (A3): Si and O are as defined above, and            S is sulfur;        -   w is an integer selected from 2 and 3;        -   x is an integer selected from 0 and 1;        -   and w+x=3;            (R⁹O)_(y)(R¹⁰)_(z)Si—R¹¹—N(SR¹² ₃)₂  (A4)        -   wherein in formula (A4): Si and O are as defined above, and            N is nitrogen;        -   y is an integer selected from 2 and 3;        -   z is an integer selected from 0 and 1;        -   and y+z=3;            (Si(OR¹³)₃)₂(Si(OR¹⁴)₂)_(p)  (A5)        -   wherein in formula (A5): Si and O are as defined above;        -   p is an integer selected from 1 to 10;        -   and wherein R1, R2, R3, R4, R5, R6, R8, R9, R10, R12, R13            and R14 in the above formulae (A1) to (A5) independently are            selected from: (C6-C21) aryl, (C7-C22) alkylaryl and            (C1-C16) alkyl; and        -   R7 and R11 in formulae (A3) and (A4) independently are a            divalent (C6-C21) aryl group, a divalent (C7-C22) alkylaryl            group, or a divalent (C1-C16) alkylen group;    -   iii) Adding S₂Cl₂, SCl₂, SOCl₂, S₂Br₂, SOBr₂ or a mixture        thereof to the reaction mixture; and    -   iv) optionally adding a protic agent to the reaction mixture so        as to deactivate the catalyst or other process components.

It has been found that carrying out the process in the order describedabove leads to a polymer, especially rubber, with superior properties incomparison to other polymers, especially rubbers, which are obtained inaccordance with standard procedures. Improved properties include reducedsolution viscosities as compared to linear diene polymers of similarmolecular weight Mw. This allows for a better processing of the polymersin a polymer manufacturing plant. For example, the production throughputcan be increased. Surprisingly, the process according to the inventionprovides polymers that show the above improvement without losing otherdesirable characteristics. In particular, surprisingly Mooneyviscosities of polymer compositions obtained upon mixing the polymersaccording to the invention with fillers can be maintained at relativelylow Mooney viscosity values as compared to Mooney viscosities of polymercompositions made by using state of the art polymers and fillers,provided Mooney viscosities of the compared polymers were in a similarrange.

In a second aspect, the present invention thus relates to the dienepolymers that are obtainable according to the process described herein.In a third aspect, the invention further addresses products comprisingthe diene polymer described above. Products include cured polymers andformulations comprising cured polymer and a filler.

The catalyst composition used in the process according to the inventionmay either comprise at least one compound of a rare earth element aswell as an activator compound, wherein the at least one compound of therare earth element (in the following also abbreviated as “rare earthelement compound”) is selected from carboxylates, alkyl phosphates,alkyl phosphites, alcoholates, amides and hydrocarbyls of a rare earthelement having an atomic number of 57 to 71 in the periodic table. Orthe catalyst composition may comprise a reaction product of the at leastone activator compound and the at least one rare earth element compound.

The rare earth element in the rare earth element compound is preferablyselected from neodymium, praseodymium, cerium, lanthanum, gadolinium anddysprosium or a combination thereof. In a more preferred embodiment, therare earth element comprises neodymium.

The rare earth element compound can be selected from a wide variety ofcarboxylates, alkyl phosphates, alkyl phosphites, alcoholates, amidesand hydrocarbyls. Preferred examples of carboxylates include octanoates(such as 2-ethyl-hexanoate), decanoates, naphtenates, versatate andneodecanoate. Preferred carboxylates include versatate and neodecanoate.

In a preferred embodiment, the rare earth element compound comprisesneodymium versatate or neodymium neodecanoate, preferably neodymium(versatate)₃ or neodymium (neodecanoate)₃.

The activator compound of the catalyst composition as used in thepresent invention preferably comprises a Lewis acid. The Lewis acid canbe chosen from a wide variety of Lewis acids, such as alkyl aluminumhalides, alkyl chlorides, chlorosilanes and other metal chlorides. In amore preferred embodiment, the Lewis acid is an alkyl aluminum chlorideor bromide selected from dialkyl aluminum chloride or bromide and alkylaluminum dichloride or dibromide. Suitable examples of alkyl aluminumchlorides include diethyl aluminum chloride, ethyl aluminumsesquichloride, ethyl aluminum dichloride, as well as di-iso-butylaluminum chloride, iso-butyl aluminum sesquichloride, iso-butyl aluminumdichloride, di-iso-propyl aluminum chloride, iso-propyl aluminumsesquichloride and iso-propyl aluminum dichloride. Examples of alkylaluminum bromides include diethyl aluminum bromide, ethyl aluminumsesquibromide, ethyl aluminum dibromide, as well as di-iso-butylaluminum bromide, iso-butyl aluminum sesquibromide, iso-butyl aluminumdibromide, di-iso-propyl aluminum bromide, iso-propyl aluminumsesquibromide and iso-propyl aluminum dibromide. In a particularlypreferred embodiment, the Lewis acid is selected from diethyl aluminumchloride, ethyl aluminum sesquichloride, ethyl aluminum dichloride,iso-butyl aluminum chloride, iso-butyl aluminum sesquichloride,iso-butyl aluminum dichloride, di-iso-propyl aluminum chloride,iso-propyl aluminum sesquichloride and iso-propyl aluminum dichloridewith diethyl aluminum chloride being particularly preferable.

Alkyl aluminum halides as activator compounds are typically used in anamount such that the ratio of the rare earth element compound/alkylaluminum halide is of from 1:1 to 1:3 based on the molar amount of therare earth element and the molar equivalents of halide. Preferably, thisratio is of from 1:2 to 1:3.

In a further preferred embodiment, the activator compound of thecatalyst composition comprises one or more dialkyl aluminum hydridesaccording to general formula (A6) and at least one of the above Lewisacids:R¹⁵ ₂AlH  (A6)

wherein both groups R¹⁵ in formula (A6) are independently C₁₋₁₀ alkylgroups. Preferably, each R¹⁵ is a C₂₋₆ alkyl group, more preferably aC₃₋₄ alkyl group. Particularly preferred examples of R¹⁵ are iso-propyland isobutyl.

The dialkyl aluminum hydride according to formula (A6) is typically usedin an amount such that the molar ratio of the dialkyl aluminumhydride/rare earth element compound is of from 3:1 to 30:1, preferablyof from 5:1 to 15:1.

Further activating compounds that may be used as an alternative to or inaddition to the above at least one activator compound are combinationsof neutral optional Lewis acids, especially the combination of atrialkyl aluminum compound having from 1 to 4 carbons in each alkylgroup with one or more C1-30 hydrocarbyl-substituted Group 13 Lewis acidcompounds, especially halogenated tri(hydrocarbyl)boron or -aluminumcompounds having from 1 to 20 carbons in each hydrocarbyl group,especially tris(pentafluorophenyl)borane ortris(pentafluorophenyl)alumane, further combinations of such neutralLewis acid mixtures with a polymeric or oligomeric alumoxane, andcombinations of a single neutral Lewis acid, especiallytris(pentafluorophenyl)borane or tris(pentafluorophenyl)alumane, with apolymeric or oligomeric alumoxane. A benefit according to the presentinvention is the discovery that the most efficient catalyst activationusing such a combination of tris(pentafluorophenyl)borane/alumoxanemixture occurs at reduced levels of alumoxane. Preferred molar ratios ofthe metal complex:tris(pentafluorophenyl)borane:alumoxane are from 1:1:1to 1:5:5, more preferably from 1:1:1.5 to 1:5:3. The surprisingefficient use of lower levels of alumoxane with the present inventionallows for the production of diene polymers with high catalyticefficiencies using less of the expensive alumoxane activator.Additionally, polymers with lower levels of aluminum residue, and hencegreater clarity, are obtained.

Suitable ion-forming activator compounds useful as activators in oneembodiment of the present invention comprise a cation which is a acidcapable of donating a proton, and a compatible, non-coordinating orpoorly coordinating anion. As used herein, the term “non-coordinating”means an anion or substance which either does not coordinate to themetal containing precursor complex and the catalytic derivative derivedtherefrom, or which is only weakly coordinated to such complexes therebyremaining sufficiently labile to be displaced by a Lewis base such asolefin monomer in a manner such that the polymerization may proceed. Anon-coordinating anion specifically refers to an anion which whenfunctioning as a charge-balancing anion in a cationic metal complex doesnot transfer an anionic substituent or fragment thereof to said cationthereby forming neutral complexes. “Compatible anions” are anions whichare not degraded to neutrality when the initially formed complexdecomposes and are non-interfering with desired subsequentpolymerization or other uses of the complex.

Preferred anions are those containing a single coordination complexcomprising a charge-bearing metal or metalloid core which anion iscapable of balancing the charge of the active catalyst species (themetal cation) which may be formed when the two components are combined.Also, said anion should be sufficiently labile to be displaced byolefinic, diolefinic and acetylenically unsaturated compounds or otherneutral Lewis bases such as ethers or nitriles. Suitable metals include,but are not limited to, aluminum, gold and platinum. Suitable metalloidsinclude, but are not limited to, boron, phosphorus, and silicon.Compounds containing anions which comprise coordination complexescontaining a single metal or metalloid atom are, of course, well knownand many, particularly such compounds containing a single boron atom inthe anion portion, are available commercially.

Preferably such activators may be represented by the following generalformula:(L*−H)+dAd−

wherein:

-   -   L* is a neutral Lewis base;    -   (L*−H)+ is a Brönsted acid;    -   Ad− is a noncoordinating, compatible anion having a charge of        d−, and    -   d is an integer from 1 to 3.    -   More preferably Ad− corresponds to the formula:        [M*Q4]−;    -   wherein:    -   M* is boron or aluminum in the +3 formal oxidation state; and    -   Q independently each occurrence is selected from hydride,        dialkylamido, halide, hydrocarbyl, halohydrocarbyl, halocarbyl,        hydrocarbyloxide, hydrocarbyloxy substituted-hydrocarbyl,        organometal substituted-hydrocarbyl, organometalloid        substituted-hydrocarbyl, halohydrocarbyloxy, halohydrocarbyloxy        substituted hydrocarbyl, halocarbyl-substituted hydrocarbyl, and        halo-substituted silyihydrocarbyl radicals (including        perhalogenated hydrocarbyl-, perhalogenated hydrocarbyloxy- and        perhalogenated silythydrocarbyl radicals), said Q having up to        20 carbon atoms with the proviso that in not more than one        occurrence is Q halide. Examples of suitable hydrocarbyloxide Q        groups are disclosed in U.S. Pat. No. 5,296,433.

In a more preferred embodiment, d is one, that is, the counterion has asingle negative charge and is A−. Activating cocatalysts comprisingboron which are particularly useful in the preparation of catalysts ofthis invention may be represented by the following general formula:(L*−H)+(BQ4)−;

wherein:

-   -   (L*−H)+ is as previously defined;    -   B is boron in a formal oxidation state of 3; and    -   Q is a hydrocarbyl-, hydrocarbyloxy-, fluorinated hydrocarbyl-,        fluorinated hydrocarbyloxy-, or fluorinated        silythydrocarbyl-group of up to 20 nonhydrogen atoms, with the        proviso that in not more than one occasion is Q hydrocarbyl.

Even more preferably, Q is each occurrence a fluorinated aryl group,especially, a pentafluorophenyl or nonafluorobiphenyl group. PreferredBQ4-anions are methyltris(pentafluorophenyl)borate,tetrakis(pentafluorophenyl)borate or tetrakis(nonafluorobiphenyl)borate.

Illustrative, but not limiting, examples of boron compounds which may beused as an activating cocatalyst in the preparation of the improvedcatalysts of this invention are trisubstituted ammonium salts such as:trimethylammonium tetraphenylborate, tri(n-butyl)ammoniumtetraphenylborate, methyldioctadecylammonium tetraphenylborate,triethylammonium tetraphenylborate, tripropylammonium tetraphenylborate,tri(n-butyl)ammonium tetraphenylborate,methyltetradecyloctadecylammonium tetraphenylborate,N,N-dimethylanilinium tetraphenylborate, N,N-diethylaniliniumtetraphenylborate, N,N,-2,4,6-pentamethylanilinium) tetraphenylborate,N,N-dimethyl anilinium bis(7,8-dicarbundecaborate) cobaltate (III),trimethylammonium tetrakis(pentafluorophenyl)borate,methyldi(tetradecyl)ammonium tetrakis(pentafluorophenyl) borate,methyldi(octadecyl)ammonium tetrakis(pentafluorophenyl) borate,triethylammonium tetrakis(pentafluorophenyl)borate, tripropylammoniumtetrakis(pentafluorophenyl)borate, tri(n-butyl)ammoniumtetrakis(pentafluorophenyl)borate, tri(sec-butyl)ammoniumtetrakis(pentafluorophenyl)borate, N,N-dimethylaniliniumtetrakis(pentafluorophenyl)borate, N,N-diethylaniliniumtetrakis(pentafluorophenyl)borate, N,N,2,4,6-pentamethylanilinium)tetrakis(pentafluorophenyl)borate, trimethylammoniumtetrakis(2,3,4,6-tetrafluorophenyl)borate, triethylammoniumtetrakis(2,3,4,6-tetrafluorophenyl)borate, tripropylammoniumtetrakis(2,3,4,6-tetrafluorophenyl)borate, tri(n-butyl)ammoniumtetrakis(2,3,4,6-tetrafluorophenyl) borate, dimethyl(t-butyl) ammoniumtetrakis(2,3,4,6-tetrafluorophenyl)borate, N,N-dimethylaniliniumtetrakis(2,3,4,6-tetrafluorophenyl) borate, N,N-diethylaniliniumtetrakis(2,3,4,6-tetrafluorophenyl) borate, andN,N,2,4,6-pentamethylanilinium)tetrakis-(2,3,4,6-tetrafluorophenyl)borate; dialkyl ammonium salts suchas: di(octadecyl)ammonium tetrakis(pentafluorophenyl)borate,di(tetradecyl)ammonium tetrakis(pentafluorophenyl)borate, anddicyclohexylammonium tetrakis(pentafluorophenyl)borate; trisubstitutedphosphonium salts such as: triphenylphosphoniumtetrakis(pentafluorophenyl)borate, methyldi(octadecyl)phosphoniumtetrakis(pentafluorophenyl) borate, andtris(2,6-dimethylphenyl)phosphonium tetrakis(pentafluorophenyl)borate.

Examples for tetrakis(pentafluorophenyl)borate salts are long chainalkyl mono-di- and trisubstituted ammonium complexes, especially C14-C20alkyl ammonium complexes, especially methyldi(octadecyl) ammoniumtetrakis (pentafluorophenyl)borate and methyldi(tetradecyl)ammoniumtetrakis(pentafluorophenyl)borate, or mixtures including the same. Suchmixtures include protonated ammonium cations derived from aminescomprising two C14, C16 or C18 alkyl groups and one methyl group. Suchamines are available from Witco Corp., under the trade name Kemamine™T9701, and from Akzo-Nobel under the trade name Armeen™ M2HT.

Examples of the catalyst activators herein include the foregoingtrihydrocarbylammonium-, especially, methylbis(tetradecyl)ammonium- ormethylbis(octadecyl)ammonium-salts of:bis(tris(pentafluorophenyl)borane)imidazolide,bis(tris(pentafluorophenyl)borane)-2-undecylimidazolide,bis(tris(pentafluorophenyl)borane)-2-heptadecylimidazolide,bis(tris(pentafluorophenyl)borane)-4,5-bis(undecyl)imidazolide,bis(tris(pentafluorophenyl) borane)-4,5-bis(heptadecyl)imidazoide,bis(tris(pentafluorophenyl)borane)imidazolinide,bis(tris(pentafluorophenyl)borane)-2-undecylimidazolinide,bis(tris(pentafluorophenyl)borane)-2-heptadecylimidazolinide,bis(tris(pentafluorophenyl)borane)-4,5-bis(undecyl)imidazolinide,bis(tris(pentafluorophenyl)borane)-4,5-bis(heptadecyl)imidazolinide,bis(tris(pentafluorophenyl)borane)-5,6-dimethylbenzimidazolide,bis(tris(pentafluorophenyl)borane)-5,6-bis(undecyl)benzimidazolide,bis(tris(pentafluorophenyl)alumane)imidazolide,bis(tris(pentafluorophenyl)alumane)-2-undecylimidazolide,bis(tris(pentafluorophenyl)alumane)-2-heptadecylimidazolide,bis(tris(pentafluorophenyl)alumane)-4,5-bis(undecyl)imidazolide,bis(tris(pentafluorophenyl)alumane)-4,5-bis(heptadecyl)imidazolide,bis(tris(pentafluorophenyl)alumane)imidazolinide,bis(tris(pentafluorophenyl)alumane)-2-undecylimidazolinide,bis(tris(pentafluorophenyl)alumane)-2-heptadecylimidazolinide,bis(tris(pentafluorophenyl)alumane)-4,5-bis(undecyl)imidazolinide,bis(tris(pentafluorophenyl)alumane)-4,5-bis(heptadecyl)imidazolinide,bis(tris(pentafluorophenyl)alumane)-5,6-dimethylbenzimidazolide, andbis(tris(pentafluorophenyl)alumane)-5,6-bis(undecyl)benzimidazolide. Theforegoing activating cocatalysts have been previously taught withrespect to different metal complexes in the following reference: EP 1560 752 A1.

Another suitable ammonium salt, especially for use in heterogeneouscatalyst compositions, is formed upon reaction of an organometalcompound, especially a tri(C1-6 alkyl)aluminum compound with an ammoniumsalt of a hydroxyaryltris(fluoroaryl)borate compound. The resultingcompound is an organometaloxyaryltris(fluoroaryl)borate compound whichis generally insoluble in aliphatic liquids. Examples of suitablecompounds include the reaction product of a tri(C1-6 alkyl)aluminumcompound with the ammonium salt of hydroxyaryltris(aryl)borate. Suitablehydroxyaryltris(aryl)borates include the ammonium salts, especially theforegoing long chain alkyl ammonium salts of:(4-dimethylaluminumoxyphenyl)tris(pentafluorophenyl) borate,(4-dimethylaluminumoxy-3,5-di(trimethylsilyl)phenyl)tris(pentafluorophenyl)borate,(4-dimethylaluminumoxy-3,5-di(t-butyl)phenyl)tris(pentafluorophenyl)borate, (4-dimethylaluminumoxybenzyl)tris(pentafluorophenyl) borate, (4-dimethylaluminumoxy-3-methylphenyl)tris(pentafluorophenyl)borate, (4-dimethylaluminumoxy-tetrafluorophenyl)tris(pentafluorophenyl)borate, (5-dimethylaluminumoxy-2-naphthyl)tris(pentafluorophenyl)borate, 4-(4-dimethylaluminumoxyphenyl)phenyltris(pentafluorophenyl)borate,4-(2-(4-(dimethylaluminumoxyphenyl)propane-2-yl)phenyloxy)tris(pentafluorophenyl)borate, (4-diethylaluminumoxyphenyl)tris(pentafluorophenyl) borate,(4-diethylaluminumoxy-3,5-di(trimethylsilyl)phenyl)tris(pentafluorophenyl)borate,(4-diethylaluminumoxy-3,5-di(t-butyl)phenyl)tris(pentafluorophenyl)borate, (4-diethylaluminumoxybenzyl)tris(pentafluorophenyl)borate, (4-diethylaluminumoxy-3-methylphenyl)tris(pentafluorophenyl)borate, (4-diethylaluminumoxy-tetrafluorophenyl)tris(pentafluorophenyl)borate, (5-diethylaluminumoxy-2-naphthyl)tris(pentafluorophenyl) borate, 4-(4-diethylaluminumoxyphenyl)phenyltris(pentafluorophenyl)borate,4-(2-(4-(diethylaluminumoxyphenyl)propane-2-yl)phenyloxy)tris(pentafluorophenyl)borate, (4-diisopropylaluminumoxyphenyl)tris(pentafluorophenyl)borate,(4-diisopropylaluminumoxy-3,5-di(trimethylsilyl)phenyl)-tris(pentafluorophenyl)borate,(4-diisopropylaluminumoxy-3,5-di(t-butyl)phenyl)tris(pentafluorophenyl)borate, (4-diisopropylaluminumoxybenzyl)tris(pentafluorophenyl)borate, (4-diisopropylaluminumoxy-3-methylphenyl)tris(pentafluorophenyl)borate,(4-diisopropylaluminumoxy-tetrafluorophenyl)tris(pentafluorophenyl)borate, (5-diisopropylaluminumoxy-2-naphthyl)tris(pentafluorophenyl)borate, 4-(4-diisopropylaluminumoxyphenyl)phenyltris(pentafluorophenyl)borate, and4-(2-(4-(diisopropylaluminumoxyphenyl)propane-2-yl)phenyloxy)tris(pentafluorophenyl)borate.

Especially preferred ammonium compounds are methyldi(tetradecyl)ammonium(4-diethylaluminumoxyphenyl) tris(pentafluorophenyl)borate,methyldi(hexadecyl)ammonium (4-diethylaluminumoxyphenyl)tris(pentafluorophenyl)borate, methyldi(octadecyl)ammonium(4-diethylaluminumoxyphenyl) tris(pentafluorophenyl) borate, andmixtures thereof. The foregoing complexes are disclosed in U.S. Pat.Nos. 5,834,393 and 5,783,512.

Another suitable ion-forming, activating compound comprises a salt of acationic oxidizing agent and a noncoordinating, compatible anionrepresented by the formula:(Oxe+)d(Ad−)e,

wherein

-   -   Oxe+ is a cationic oxidizing agent having a charge of e+;    -   d is an integer from 1 to 3;    -   e is an integer from 1 to 3; and    -   Ad− is as previously defined.

Examples of cationic oxidizing agents include: ferrocenium,hydrocarbyl-substituted ferrocenium, Pb+2 or Ag+. Preferred embodimentsof Ad− are those anions previously defined with respect to the Bronstedacid containing activating cocatalysts, especiallytetrakis(pentafluorophenyl)borate.

Another suitable ion-forming, activating compound comprises a compoundwhich is a salt of a carbenium ion and a noncoordinating, compatibleanion represented by the formula@+A−

wherein:

-   -   @+ is a C1-20 carbenium ion; and    -   A− is a noncoordinating, compatible anion having a charge of −1.        A preferred carbenium ion is the trityl cation, especially        triphenylmethylium.

Preferred carbenium salt activating cocatalysts are triphenylmethyliumtetrakis(pentafluorophenyl)borate, triphenylmethyliumtetrakis(nonafluorobiphenyl)borate, tritolylmethyliumtetrakis(pentafluorophenyl)borate and ether substituted adducts thereof.The activating compounds may also be used in combination. An especiallypreferred combination is a mixture of a tri(hydrocarbyl)aluminum ortri(hydrocarbyl)borane compound having from 1 to 4 carbons in eachhydrocarbyl group with an oligomeric or polymeric alumoxane compound.

The molar ratio of the rare earth element compound/the at least oneactivator compound typically ranges of from 1:10,000 to 10:1, preferablyof from 1:5000 to 10:1, more preferably of from 1:2500 to 1:1.

Alumoxane, when used by itself as an activating compound, is preferablyemployed in large molar ratio, generally at least 50 times the quantityof the rare earth element compound on a molar basis.Tris(pentafluorophenyl)borane, where used as an activating compound, ispreferably employed in a molar ratio to the rare earth element compoundof from 0.5:1 to 10:1, more preferably from 1:1 to 6:1, most preferablyfrom 1:1 to 5:1.

If the above-mentioned ion-forming compound comprising a compatiblenon-coordinating or poorly coordinating anion is used as an activatingcompound, it is preferable for the rare earth element compound accordingto the invention to be alkylated. Activators comprising boron arepreferred.

Further activating compounds for use herein are combinations of neutraloptional Lewis acids, especially the combination of a trialkyl aluminumcompound having from 1 to 4 carbons in each alkyl group with one or moreC1-30 hydrocarbyl-substituted Group 13 Lewis acid compounds, especiallyhalogenated tetrakis(hydrocarbyl)boron or -aluminum compounds havingfrom 1 to 20 carbons in each hydrocarbyl group, especiallytetrakis(pentafluorophenyl)borate,tetrakis(3,5-bis(trifluoromethyl)phenyl)borate, further combinations ofa single neutral Lewis acid, especiallytetrakis(pentafluorophenyl)borate ortetrakis(3,5-bis(trifluoromethyl)phenyl)borate, with a polymeric oroligomeric alumoxane. A benefit according to the present invention isthe discovery that the most efficient catalyst activation using such acombination of tetrakis(pentafluorophenyl)borate/alumoxane mixtureoccurs at reduced levels of alumoxane.

Preferred molar ratios of the rare earth compound:tetrakis(pentafluorophenyl)borate:alumoxane from 1:1:1 to 1:5:1.000,more preferably from 1:1:1.5 to 1:5:500. The surprising efficient use oflower levels of alumoxane with the present invention allows for theproduction of diene polymers with high catalytic efficiencies using lessof the expensive alumoxane activator. Additionally, polymers with lowerlevels of aluminum residue, and hence greater clarity, are obtained.Preferred molar ratios of the metalcomplex:tetrakis(pentafluorophenyl)borate:neutral optional Lewis acidsespecially trialkyl aluminum or dialkyl aluminum hydride compounds arefrom 1:1:10 to 1:10:1000, more preferably from 1:1:20 to 1:5:500. Alsoin this case polymers are obtained with lower levels of aluminumresidue, and hence greater clarity, are obtained.

The catalyst composition used in the process according to the inventioneither comprises at least one of the above rare earth element compoundsas well as at least one of the activator compounds identified above, orthe catalyst composition may comprise a reaction product of theactivator compound and the rare earth element compound.

The catalyst composition may be formed, e.g. in situ in thepolymerization reactor by adding the individual components of thecatalyst composition (i.e. the rare earth element compound and the atleast one activator compound) to a solution of the monomers. The term“in situ” in the context of the present invention means that thecatalyst composition is not isolated prior to its use. For such aformation, at least one component of the catalyst composition is addedindividually. If the catalyst composition comprises a dialkyl aluminumhydride according to general formula (A6) and an alkyl aluminum chlorideas a Lewis acid, then it may be preferable to, e.g. add the rare earthelement compound and the dialkyl aluminum hydride to the polymerizationreactor comprising the Lewis acid and a solution of monomers. In anycase, it is to be understood that at least three molar equivalents of aconjugated diene monomer should be present before adding the activatorcompound to the rare earth element compound so as to avoid catalystdeactivation.

The catalyst composition may be formed, e.g. in situ in thepolymerization reactor, for example by contacting the rare earth elementcompound and the activator compound on a support as a carrier. Thesupport (hereinafter also referred to as “carrier”) can be chosen from:clay, silica, charcoal (activated carbon), graphite, expanded clay,expanded graphite, carbon black, layered silicates, and alumina. Claysand layered silicates include, but are not limited to, magadiite,montmorillonite, hectorite, sepiolite, attapulgite, smectite, andlaponite. Supported catalyst compositions of the invention may beprepared by several methods. For example, the rare earth elementcompound and optionally the activator compound can be combined beforethe addition of the support material. As discussed herein below, themixture may be prepared in a conventional solution using a solvent. Thesolvent is preferably also suitable for use as a polymerization diluentfor the liquid phase polymerization of an olefin monomer. Alternatively,the activator compound can be placed on the support material followed bythe addition of the rare earth element compound or conversely, the rareearth element compound may be applied to the support material followedby the addition of the activator compound. The catalyst can be supportedonto the carrier material using techniques such as solid-phaseimmobilization (SPI) described by H. C. L. Abbenhuis in Angew. Chem.Int. Ed. 37 (1998) 356-58 and by M. Buisio et al., in MicroporousMater., 5 (1995) 211 and by J. S. Beck et al., in J. Am. Chem. Soc., 114(1992) 10834, as well as pore volume impregnation (PVI) (see WO97/24344). The isolation of the impregnated carrier can be done byfiltration or by removing the volatile material present (i.e., solvent)under reduced pressure or by heating.

The support, if present, is preferably employed in an amount to providea weight ratio of catalyst composition (based on metal):support from1:100,000 to 1:10, more preferably from 1:50,000 to 1:20, and mostpreferably from 1:10,000 to 1:30.

Instead of forming the catalyst composition in situ, the catalystcomposition can also be preformed, for example by subjecting the rareearth element compound and the activator compound to an aging reactionin an aging reactor wherein a limited amount of diene is added to amixture of the rare earth element compound and activator compound.

The catalyst composition may be formed in a suitable non-interferingsolvent or reaction medium at a temperature of from −78° C. to 250° C.,preferably of from −5° C. to 160° C., more preferably of from 10° C. to110° C. Suitable reaction media for the formation of the catalystcomposition are aliphatic and aromatic hydrocarbons andhalohydrocarbons. Examples include straight and branched-chainhydrocarbons such as isobutane, butane, pentane, hexane, heptane,octane, and mixtures thereof, cyclic and alicyclic hydrocarbons such ascyclohexane, cycloheptane, methylcyclohexane, methylcycloheptane, andmixtures thereof; chlorinated-, fluorinated- or chlorofluorinatedhydrocarbons such as chloroform, dichloromethane, chlorobenzene,dichlorobenzene, and perfluorinated C4-10 alkanes; aromatic andhydrocarbyl-substituted aromatic compounds such as benzene, toluene,xylene, and styrene. If the catalyst composition is not formed in situ,the reaction medium used for forming the catalyst composition is in onepreferred option the same reaction medium as the one used inpolymerization step i), obviating the need to use a secondary solventsystem.

If the catalyst composition is not formed in situ, the reaction mediumused for forming the catalyst composition may then in another preferredoption correspond to one of the solvents used the reaction medium inpolymerization step i), obviating the need to use a secondary solventsystem.

Separately prepared or preformed catalyst compositions can be stored atroom temperature or even at elevated temperatures such as, for example,but not limited to, 50° C., in the solid state for extended periods oftime. In addition, solutions of the catalyst compositions may be storedat room temperature before use. This greatly increases the flexibilityof production in an industrial plant. A separately prepared (orpreformed) catalyst composition usually does not require a separateaging step and if it is desirable to employ an optional aging step, itadvantageously does not require long aging times. In case of a preformedcatalyst, it is possible to start the polymerization reaction by addingthe catalyst composition and the one or more diene monomer in any orderinto the polymerization reactor. The polymerization can be started forexample either by addition of the catalyst composition to the monomer orby the addition of the one or more diene monomers as the last component.Alternatively, the catalyst composition—i.e. its individual components(including the rare earth element compound and the activator compound)or a reaction product hereof—or a solution thereof, may be fed to thepolymerization reactor simultaneously during addition of the one or morediene monomers.

In the polymerization process, the catalyst composition is used in acatalytically effective amount, i.e., any amount that successfullyresults in the formation of a polymer. Such amounts may be readilydetermined by routine experimentation by the worker skilled in the art,but typically the molar ratio of catalyst composition:diene monomers isfrom 10⁻¹²:1 to 10⁻¹:1, more preferably from 10⁻¹²:1 to 10⁻³:1.

The catalyst composition may also be utilized in combination with atleast one additional homogeneous or heterogeneous polymerizationcatalyst in the same or in separate reactors connected in series or inparallel to prepare polymer blends having desirable properties, such asfor example a different molecular weight distribution, including abimodal molecular weight distribution. An example of such a process isdisclosed in WO 94/00500, equivalent to U.S. Ser. No. 07/904,770, aswell as U.S. Pat. No. 5,844,045. In case of solution orsuspension/slurry type polymerizations as described herein below, thequantity of rare earth metal comprised in the catalyst composition to beused generally is such that its concentration in the solvent ordispersion agent amounts to 10⁻⁸-10⁻³ mol/L, preferably 10⁻⁷-10⁻⁴ mol/L.

Step i) of polymerizing the at least one diene monomer is preferablyconducted at a temperature of between −50 and +250° C., preferablybetween −5 and +160° C., more preferably between 10° C. and 110° C.

In general, homo- and co-polymerization of the conjugated diene monomersmay be accomplished at conditions well known in the art forZiegler-Natta or Kaminsky-Sinn type polymerization reactions, such as attemperatures of from −50 to 250° C. The polymerization is generallyconducted under batch, continuous or semicontinuous polymerizationconditions. The polymerization process can be conducted as a gas phasepolymerization (e.g. in a fluidized bed or stirred bed reactor), as asolution polymerization, wherein the homopolymer or copolymer formed issubstantially soluble in the reaction mixture, a suspension/slurrypolymerization, wherein the polymer formed is substantially insoluble inthe reaction medium, as a solid phase powder polymerization or as aso-called bulk polymerization process, in which case an excess ofmonomer to be polymerized is used as the reaction medium. Preferably,the process according to the present invention is conducted undersolution or bulk polymerization conditions. The polymerization may beconducted in one or more continuous stirred reactors or fluidized bed,gas phase reactors, connected in series or parallel. Monomer and/orsolvent may be added to the reactor as is well known in the art. Acontinuous process is preferred, in which event advantageously, e.g. amixture of the reaction components including catalyst composition,solvent and dienes is substantially supplied continuously or at frequentintervals into the reactor system, and polymerization is continuouslymonitored so as to ensure an efficient reaction and the production ofthe desired product which is continuously removed. For example, it iswell known that many supported coordination catalysts and catalystcompositions for polymerization processes are highly sensitive, invarying degrees, to catalyst poisons such as water, oxygen, carbonoxides, acetylenic compounds and sulfur compounds. Introduction of suchcompounds may result in reactor upset and production of off-gradeproduct. Typically, computer control and monitoring systems may be usedto maintain process variables within acceptable limits, often bymeasuring polymer variables such as temperature, viscosity, molecularweight, flow rates or catalyst productivity. If the polymerizationprocess is carried out under suspension or gas phase polymerizationconditions, the temperatures typically are below 150° C.

The polymerization can be effected at atmospheric pressure, atsub-atmospheric pressure, or at elevated pressure of up to, or evenhigher than 500 MPa, continuously or discontinuously. Preferably, thehomo- or copolymerization is performed at a pressure of from 0.01 to 500MPa, more preferably at a pressure of from 0.01 to 10 MPa, mostpreferably at a pressure of from 0.1 to 2 MPa. Slurry and solutionpolymerizations normally take place at relatively low pressures,preferably at a pressure of less than 10 MPa. The polymerization can becarried out in the gas phase as well as in a liquid reaction medium.

The catalyst composition may be used to homopolymerize or copolymerizeone or more diene monomers, preferably conjugated diene monomers havingfrom 4 to 50 preferably from 4 to 12 carbon atoms either alone to givehomopolymers or in combination with at least one different type of dienemonomer or with a type of alpha-olefines for copolymers. Preferredmonomers include conjugated dienes chosen from the group comprisinginternal conjugated olefins, cyclic conjugated olefins and non-cyclicconjugated olefins. Preferred conjugated dienes are 1,3-butadiene,isoprene (2-methyl-1,3-butadiene), 2,3-dimethyl-1,3-butadiene,1,3-pentadiene, 2,4-hexadiene, 1,3-hexadiene, 2,4-hexadiene,1,3-heptadiene, 1,3-octadiene, 2-methyl-2,4-pentadiene, cyclopentadiene,2,4-hexadiene, 1,3-cyclooctadiene. Preferred alpha-olefine monomers foruse as a comonomer in the polymerization of diene monomers are selectedfrom ethene, propene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene,1-octene, styrene, alpha methylstyrene, divinyl benzene, acrylonitrile,acrylic acid ester, methylmethacrylate, ethylmethacrylate andn-butylmethacrylate. Ethylene, propene and styrene are preferredalpha-olefins.

Especially desirable polymers that are obtainable according to thepresent invention are homo-, co- and terpolymers of conjugated dienes,especially butadiene or isoprene, and random or block copolymers of atleast one conjugated diene, especially butadiene, with at least onedifferent type of conjugated diene, especially isoprene. Especiallypreferred are the homopolymerization of butadiene or isoprene as well asrandom or block copolymerizations, optionally terpolymerizations, of atleast one conjugated diene, especially butadiene with at least onedifferent type of conjugated diene, especially isoprene. Particularlypreferred homopolymers are polybutadiene, and particularly preferredcopolymers are copolymers of butadiene, isoprene and/or styrene.Butadiene and isoprene can be used as monomers regardless of theirorigin, including biochemical monomer synthesis processes, for examplestarting from biomass readily available, for example sugar.

In a preferred embodiment, dienes which can be used in the processaccording to the invention thus comprise at least one of butadiene,isoprene, pentadiene and 2,3-dimethylbutadiene, or a mixture of two ormore of the monomers. In a preferred embodiment, the one or more dienemonomers that are polymerized in step i) thus comprise at least one ofthese components. Depending on the polymer to be produced, step i) ofpolymerizing one or more diene monomers comprises a mixture of thesedienes, e.g. a mixture of butadiene and isoprene. In a furtherembodiment, other monomers can be incorporated in polymerization step i)in addition to the one or more diene monomers indicated above. Forexample, such monomers preferably include styrene.

In a further embodiment, step i) of polymerizing one or more dienes isconducted in the presence of an organic solvent. Examples of suitablesolvents include aromatic, aliphatic and/or cycloaliphatic hydrocarbonssuch as benzene, pentane, n-hexane, isohexane, heptane and/orcyclohexane. Preferably, polymerization is carried out in the presenceof one of these solvents or a mixture thereof. Preferably, the inertorganic solvent is used in amounts from 200 to 900 parts by weight,based on 100 parts by weight of monomer.

In one embodiment, polymerization step i) is carried out up to aconversion of as much as 99.9% of the diene monomers. Typically, thereaction mixture reaches 70% conversion or more, preferably 90%conversion or more, more preferably 95% or more, even more preferably98% or more, most preferably 98% to 99.5% before the at least onealkoxysilane compound is added in step ii). Conversion can be detectedby means of standard gravimetric methods using a Halogen MoistureAnalyzer HR73 from Mettler Toledo.

In step ii) of the present process, at least one alkoxysilane compoundis added to the reaction mixture obtained in step i). The at least onealkoxysilane compound is selected from the compounds represented by theabove formulae (A1) through (A5). Preferred alkoxysilane compounds areselected from the above formulae (A1) to (A5), wherein groups R1, R2,R3, R4, R5, R6, R8, R9, R10, R12, R13 and R14 in formulae (A1) to (A5)independently from each other are C₁₋₈ alkyl groups. In a more preferredembodiment, R1, R3, R5, R9, R13 and R14 in formulae (A1) to (A5)independently from each other are C₁₋₄ alkyl groups, preferably methylor ethyl. Preferably, the one or more alkoxysilane compounds areselected from the above formulae (A1), (A2), (A3) and (A4), morepreferably from (A1) and (A3). In a preferred embodiment of Formula(A1): if s is 1, q is an integer selected from 4; r is an integerselected from 0; and q+r=4; and if s in formula (A1) is 2, then qpreferably is an integer selected from 3; r is an integer selected from0; and q+r=3. In a preferred embodiment of Formula (A2): t is an integerselected from 3; u is an integer selected from 0; and t+u=3. In apreferred embodiment of Formula (A3): w is an integer selected from 3; xis an integer selected from 0; and w+x=3; and in a preferred embodimentof Formula (A4): y is an integer selected from 3; z is an integerselected from 0; and y+z=3.

The term “alkyl” as used throughout the invention refers to ahydrocarbon group that may be straight chain, branched or cyclic, havingthe number of carbon atoms designated (i.e. C₁₋₈ alkyl means 1-8 carbonatoms). Examples of alkyl groups include methyl, ethyl, n-propyl,isopropyl and butyl, t-butyl, isobutyl, sec-butyl, cyclohexyl,cyclopentyl, (cyclohexyl)methyl, (cyclopropyl)methyl, octane, etc. Alkylgroups can be substituted or unsubstituted. Examples of substitutedalkyl groups include haloalkyl, thioalkyl, aminoalkyl, and the like.

In a preferred embodiment, the alkoxysilane is selected from (CH₃O)₄Si,((CH₃O)₃Si)₂ and (CH₃O)₃Si—(CH₂)₃—S—Si(CH₃)₂C(CH₃)₃ and mixturesthereof.

Preferably, the amount of alkoxysilanes as added in step ii) of thepresent process is based on a molar ratio ([mol]/[mol]) of Si ascontained in the alkoxysilane compound/polymer of from 0.2 to 2,preferably of from 0.5 to 1.

Addition of the at least one alkoxysilane compound is preferably done ata temperature of from 30 to 100° C., and the at least one alkoxysilanecompound is preferably added at a pressure of from 0.2 to 5 bar.

As regards step iii) of adding S₂Cl₂, SCl₂, SOCl₂, S₂Br₂, SOBr₂ or amixture thereof to the reaction mixture obtained in step ii), typicallyless than 0.05 parts by weight, preferably 0.01 to 0.045, morepreferably 0.01 to 0.035, and even more preferably 0.01 to 0.02 parts byweight of S₂Cl₂, SCl₂, SOCl₂, S₂Br₂, SOBr₂ or a mixture thereof areadded to 100 parts by weight of diene polymer. In a preferredembodiment, S₂Cl₂ and/or S₂Br₂ are added in step iii).

It has been found that keeping the amounts of S₂Cl₂, SCl₂, SOCl₂, S₂Br₂,SOBr₂ or the mixture thereof in the indicated ranges facilitatesvaluable solution viscosities of the resulting polymer. “Valuable”solution viscosities in this context means that the solution viscositycan be reduced as compared to prior art polymers having a similar numberaverage molecular weight (Mn). At the same time these ranges allow thecomposition comprising the polymers and a filler to gain a favourableMooney viscosity value as compared to compositions which are based onconventional polymers and the filler. Therefore, the invention enablesrelatively low Mooney viscosity values in the context of compositionscomprising a polymer according to the present invention and a fillersuch as carbon black or silica if compared with the corresponding Mooneyviscosity of a composition comprising a prior art polymer and the fillerwherein both polymers (i.e. the polymer according to the invention aswell as the prior art polymer) have similar Mooney viscosity valuesbefore mixing them with the filler.

S₂Cl₂, SCl₂, SOCl₂, S₂Br₂, SOBr₂ or the mixture thereof are usuallyadded at a temperature of from 20 to 150° C., preferably at atemperature of from 30 to 120° C., more preferably at a temperature offrom 40 to 90° C.

In step iii), S₂Cl₂, SCl₂, SOCl₂, S₂Br₂, SOBr₂ or the mixture thereof isstirred with the reaction mixture for more than 1 minutes, preferablyfor about 2 to 60 minutes, more preferably for about 3 to 30 minutesbefore work up. Work up may include step iv), i.e. the optional additionof a protic agent to deactivate the catalyst composition.

The protic agent used in optional step iv) for catalyst deactivation canbe any suitable protic agent such as water, an organic acid or analcohol. Suitable organic acids include stearic acid. Suitable alcoholsinclude methanol, ethanol and iso-propanol. The amount used for catalystdeactivation preferably is in the range of from 1 to 30 Mol of proticagent per Mol of the rare earth element, more preferably of from 2 to20, most preferably of from 3 to 10 Mol of protic agent per Mol of therare earth element. Without wishing to be bound by theory, it isbelieved that addition of water, an organic acid and/or an alcohol notonly deactivates the catalyst but also renders metal organic residuesderived from the rare earth catalyst less reactive and thus lessdangerous. Removal of the catalyst composition, the thio compound andthe alkoxysilane can sometimes be omitted, particularly when thequantity of components of the catalyst composition, of the thio compoundand/or the alkoxysilane compound in the polymer or copolymer, inparticular the content of halogen and metal, is very low. If desired,however, the level of residues derived from the catalyst composition,from the thio compound or from the alkoxysilane compound in the polymer,can be reduced in a known manner, for example, by washing. Thedeactivation step can be followed by a stripping step (removal oforganic solvent(s) from the polymer). Alternatively the solvent can beremoved at reduced pressure.

The process according to the invention may involve other components. Inparticular, oils, fillers and/or vulcanizing agents may be added inadditional steps. In a further embodiment, the process according to thepresent invention thus comprises the additional step v): adding oiland/or a filler to the reaction mixture obtained in any of steps iii) oriv) or adding oil and/or a filler to the polymer obtained after solventremoval. The filler is preferably added to the polymer after completionof solvent removal.

For representative examples of oils, reference is made to InternationalPatent Application No. PCT/US09/045553 and U.S. Patent ApplicationPublication No. 2005/0159513, each of which is incorporated herein byreference in its entirety. Representative oils include but are notlimited to MES (Mild Extraction Solvate), TDAE (Treated DistillateAromatic Extract), RAE (Residual Aromatic Extract) including but notlimited to T-RAE and S-RAE, DAE including T-DAE and NAP (light and heavynaphthenic oils), including but not limited to Nytex 4700, Nytex 8450,Nytex 5450, Nytex 832, Tufflo 2000, and Tufflo 1200. In addition, nativeoils, including but not limited to vegetable oils, can be used asextender oils. Representative oils also include functionalizedvariations of the aforementioned oils, particularly epoxidized orhydroxylated oils. Aforementioned oils comprise different concentrationsof polycyclic aromatic compounds, parafinics, naphthenics and aromatics,and have different glass transition temperatures. The above mentionedtypes of oil have been characterized in “Kautschuk Gummi Kunststoffe”,vol. 52, pages 799-805. In some embodiments, the MES, RAE and TDAE arepreferred extender oils for rubber.

Examples of suitable fillers include carbon black, silica, carbon-silicadual-phase filler, clay (layered silicates), calcium carbonate,magnesium carbonate, lignin, carbon nano tubes, amorphous fillers, suchas glass particle based fillers, starch based fillers, and the like, andcombinations thereof. Further examples of fillers are described inInternational Application No. PCT/US2009/045553 fully incorporatedherein by reference. In some embodiments, the combined use of carbonblack and silica, the use of carbon-silica dual-phase-fillers alone, orthe combined use of carbon-silica dual-phase-filler and carbon blackand/or silica are employed. In a preferred embodiment, the filler isselected from silica and carbon black or a mixture hereof.

Preferred examples of carbon black include carbon black which ismanufactured by a furnace method and which has a surface area determinedby nitrogen adsorption (hereinafter also referred to as “N2A” or “BET”method) of from 50 to 200 m2/g, preferably of from 60 to 150 m2/g, andDBP oil absorption of 80-200 ml/100 grams. For example, FEF; HAF, ISAF,or SAF class carbon black may be used. In some embodiments, highagglomeration type carbon black is used. Carbon black is typically addedin an amount of from 2 to 100 parts by weight, preferably of from 5 to100 parts by weight, and more preferably of from 10 to 100 parts byweight, most preferably of from 10 to 95 parts by weight for 100 partsby weight of the polymer.

Examples of silica fillers include but are not limited to wet processsilica, dry process silica, synthetic silicate-type silica, andcombinations thereof. Silica with a small particle diameter and a highsurface area exhibits a high reinforcing effect. Small diameter, highagglomeration-type silica (i.e., having a large surface area and highoil absorptivity) exhibits excellent dispersability in the elastomericpolymer composition, representing desirable properties and superiorprocessability. In a preferred embodiment, the average particle diameterof silica, in terms of a primary particle diameter, is thus of from 5 to60 nm, preferably of from 10 to 35 nm. In a further preferred embodimentof the invention, silica having a surface area determined by nitrogenadsorption (hereinafter referred to as “N2A” or “BET” method) of from 35to 300 m2/g, preferably of from 150 to 300 m2/g is used as filler.Silica is typically added in an amount of from 2 to 100 parts by weight,preferably of from 5 to 100 parts by weight, and more preferably of from10 to 100 parts by weight, most preferably of from 10 to 95 parts byweight for 100 parts by weight of polymer.

If carbon black and silica are added together, the total amount ofcarbon black and silica preferably is of from 30 to 100 parts by weight,more preferably of from 30 to 95 parts by weight per 100 parts by weightof polymer contained in the composition comprising the polymer made bythe inventive process and the filler. So long as such fillers arehomogeneously dispersed in the composition, increasing quantities(within the above cited ranges) result in compositions having excellentrolling and extruding processability, and vulcanized products exhibitingfavorable hysteresis loss properties, rolling resistance, improved wetskid resistance, abrasion resistance, and tensile strength.

Carbon-silica dual-phase-filler may be used either independently or incombination with carbon black and/or silica in accordance with thepresent teachings. Carbon-silica dual-phase-filler can exhibit the sameeffects as those obtained by the combined use of carbon black andsilica, even in the case where it is added alone. Carbon-silicadual-phase-filler is so called silica-coated-carbon black made bycoating silica over the surface of carbon black, and is commerciallyavailable under the trademark CRX2000, CRX2002, or CRX2006 (products ofCabot Co.). Carbon-silica dual-phase-filler is added in the same amountsas previously described with respect to silica. Carbon-silicadual-phase-filler can be used in combinations with other fillersincluding but not limited to carbon black, silica, clay, calciumcarbonate, carbon nano tubes, magnesium carbonate, and combinationsthereof. In some embodiments, carbon black and silica, eitherindividually or in combination, are used.

Silica, carbon black or carbon black-silica dual-phase-fillers orcombinations thereof can be used in combination with natural fillersincluding but not limited to starch or lignin.

In yet another embodiment, the process may comprise a further step vi)of adding a vulcanizing agent and vulcanizing the polymer obtained inany of steps iii) and iv) or adding a vulcanizing agent to thecomposition obtained from step v) and vulcanizing the polymer.Preferably the vulcanizing agent is added to the composition obtained instep v). It has been found that the polymers according to the presentinvention show similar vulcanization behavior, e.g. in terms ofvulcanization kinetics, as common elastomeric polymers, in particularrubber, specifically high cis polybutadiene that are obtained accordingto standard procedures.

Sulfur, sulfur-containing compounds acting as sulfur-donors,sulfur-accelerator systems, and peroxides are the most commonvulcanizing agents. Examples of sulfur-containing compounds acting assulfur-donors include but are not limited to dithiodimorpholine (DTDM),tetramethylthiuramdisulphide (TMTD), tetraethylthiuramdisulphide (TETD),and dipentamethylenthiuramtetrasulphide (DPTT). Examples of sulfuraccelerators include but are not limited to amine derivates, guanidinederivates, aldehydeamine condensation products, thiazoles, thiuramsulphides, dithiocarbamates and thiophospahtes. Examples of peroxidesused as vulcanizing agents include but are not limited todi-tert.-butyl-peroxides, di-(tert.-butyl-peroxy-trimethyl-cyclohexane),di-(tert.-butyl-peroxy-isopropyl-)benzene, dichloro-benzoylperoxide,dicumylperoxides, tert.-butyl-cumyl-peroxide,dimethyl-di(tert.-butyl-peroxy)hexane anddimethyl-di(tert.-butyl-peroxy)hexine andbutyl-di(tert.-butyl-peroxy)valerate (Rubber Handbook, SGF, The SwedishInstitution of Rubber Technology 2000). Further examples and additionalinformation regarding vulcanizing agents can be found in Kirk-Othmer,Encyclopedia of Chemical technology 3rd, Ed., (Wiley Interscience, N.Y.1982), volume 20, pp. 365-468, (specifically “Vulcanizing Agents andAuxiliary Materials” pp. 390-402). A vulcanizing accelerator of sulfeneamide-type, guanidine-type, or thiuram-type can be used together with avulcanizing agent as required. Other additives such as zinc white,vulcanization auxiliaries, aging preventives, processing adjuvants, andthe like may be optionally added.

If added, the vulcanizing agent is typically added to the polymer or tothe composition comprising the polymer in an amount of from 0.5 to 10parts by weight, preferably of from 1 to 6 parts by weight per 100 partsby weight of polymer.

The aforementioned ranges are to be construed as disclosing each andevery value falling within the given ranges. They are merely abbreviatedrepresentations that should not be construed as not-individuallydisclosing each value within the range. Moreover, the aforementionedranges must be construed as disclosing not only the individual values ineach range but also any combination between the individual values fromthese ranges.

The process of the invention yields polymers with improved processingproperties. Without wishing to be bound by theory, it is believed thatthe improved processing behavior is the result of a specific branchingbetween the polymer chains resulting in “modified” polymers. It isassumed that the unique polymer structure is the inherent result offirst adding one or more alkoxysilane compounds to the reaction mixtureprovided in step i) before a thio compound is added to said mixture.

The polymers obtainable according to the process of the presentinvention typically have a number average molecular weight (Mn) of frombetween 75,000 and 2,500,000 g/mol preferably between 100,000 and1,500,000 g/mol and more preferably from 125,000 and 1,000,000 g/mol anda weight average molecular weight (Mw) of from between 150,000 and2,500,000 g/mol preferably between 200,000 and 1,500,000 g/mol and morepreferably from 250,000 and 1,100,000 g/mol. The preferred molecularweight distribution of the polymer, represented by the ratio of theweight average molecular weight to the number average molecular weight,(Mw/Mn), ranges from 1.0 to 10.0, preferably from 1.2 to 5.0 and morepreferably from 1.5 to 2.5.

The polymers of the present invention show reduced solution viscositiesas compared to linear polymers having a similar polymer average numbermolecular weight (Mn). A reduced solution viscosity improves the polymerproduction process, particularly in that it enables higher productionthroughput. Particularly the polymerization may lead to a higher polymerconcentration in the polymerization solvent increasing the productionrate accordingly.

While dependent upon the specific polymer and desired end useapplication, the polymers of the present invention includingoil-comprising polymers, preferably have Mooney viscosity values (ML1+4, 100° C.) as measured in accordance with ASTM D 1646 (2004) using aMonsanto MV2000 instrument, in the range of from 20 to 150, preferablyof from 25 to 120, and more preferably in the range of from 30 to 90,and most preferably of from 35 to 80. It has been found that polymerswhich are obtainable according to the present invention are particularlyfavorable in terms of processability of compositions comprising thepolymer and a filler which leads to an easier filler incorporation inthe internal mixer, improved banding on the roll mill, acceleratedextrusion rate, improved extrudate die swell, smoothness, etc.).Furthermore the polymers are beneficial in handling, green strength, anddimensional stability during storage if they have a Mooney viscosityfalling within the above range. Particularly, compositions comprising afiller and the polymer according to the present invention have a lowerpolymer composition Mooney viscosity as compared to compositions thatare not based on a polymer made by the inventive process, provided theMooney viscosities of the filler free polymers are similar.

In one embodiment, the polymers obtainable according to the process ofthe present invention have Mooney viscosities of from 35 to 60. In afurther embodiment, the polymers have Mooney viscosity values of from 60to 80. Polymers having Mooney viscosities of from 35 to 60 typicallyhave a polymer solution viscosity of less than 30000 cPoise, preferablyof less than 15000, and most preferably below 10000 cPoise at shearrates between 10 and 20 (1/s) if diluted in n-Hexane at 70° C. and 19wt.-% polymer concentration. Polymers having Mooney viscosities of from60 to 80 typically have a polymer solution viscosity of less than 40000cPoise, preferably of less than 25000, and most preferably below 15000cPoise at shear rates between 10 and 20 (1/s) if diluted in n-Hexane at70° C. and 19 wt.-% polymer concentration.

The polymers according to the present invention can favourably be usedfor making rubber products as well as objects and devices, such asproducts like tires, tire treads and tire side walls. Likewise, thepolymers of the present invention may be mixed with other polymers togive polymer blends. It is further possible to use the polymer accordingto the present invention for modifying plastics such as polystyrene,acrylonitrile-butadiene-styrene (ABS) copolymers, polyurethane orpolycarbonate.

Products, preferably cured products, comprising the polymer according tothe invention, e.g. tires, show favourable performance properties interms of, e.g. rolling resistance, wet grip, ice grip, abrasion, dynamicmodulus and heat built up.

The invention will now be described in further detail by way of thefollowing example:

EXAMPLES

Test Methods

cis-1,4- and 1,2-polybutadiene Content

The concentration of cis-1,4- and 1,2-polybutadiene was determined by IRand 13C NMR-spectroscopy. The 1D NMR spectra were collected on a BRUKERAvance 200 NMR spectrometer (BRUKER BioSpin GmbH), using a “5 mm Dualdetection probe.” The field homogeneity was optimized by maximizing thedeuterium lock signal. The samples were shimmed by optimizing thedeuterium lock signal. The samples were run at room temperature (298 K).The following deuterated solvents were used: C6D6 (7.15 ppm for 1H;128.02 ppm for 13 C), the signals of the remaining protons of deuteratedsolvents were each used as an internal reference.

For spectral processing, the BRUKER 1D WINNMR software (version 6.0) wasused. Phasing, base line correction and spectral integration of theresulting spectra was done in the manual mode. For acquisitionparameters see Table 1.

TABLE 1 1D-NMR acquisition parameters using BRUKER standard pulsesequences 1H-NMR 13C-NMR Observe frequency 200.130 MHz 50,323 MHzSpectral width 4139.073 Hz 12562.814 BRUKER Pulse program Zg30 Zgpg30Pulse angle 30° 30° Relaxation delay 1.0 s 2.0 s Number of Data pointsfor 32K 32K FT Line broadening 0.5 Hz 1 Hz Number of accumulated64 >1000    scans

Size Exclusion Chromatography

Molecular weight and molecular weight distribution of the polymer wereeach measured using Size Exclusion Chromatography (SEC) based onpolystyrene standards.

Sample Preparation:

-   -   a1) Oil free polymer samples:

About “9-11 mg” dried polymer sample (moisture content <0.6%) wasdissolved in 10 mL tetrahydrofurane, using a brown vial of 10 mL size.The polymer was dissolved by shaking the vial for 20 min at 200 u/min.

-   -   a2) oil containing polymer samples:

About “12-14 mg” dried polymer sample (moisture content <0.6%) wasdissolved in 10 mL tetrahydrofurane, using a brown vial of 10 mL size.The polymer was dissolved by shaking the vial for 20 min at 200 u/min.

-   -   b) Polymer solution was transferred into a 2 ml vial using a        0.45 μm disposable filter.    -   c) The 2 ml vial was placed on a sampler for GPC-analysis.

Elution rate: 1.00 mL/min

Injection volume: 100.00 μm (GPC-method B 50.00 μm)

The measurement was performed in THF at 40° C.). Instrument: AgilentSerie 1100/1200; Module setup: Iso pump, autosampler, thermostate,VW—Detector, RI—Detector, Degasser; Columns PL Mixed B/HP Mixed B.

In each GPC-device 3 columns were used in an connected mode. The lengthof each of the columns: 300 mm; Column Type: 79911 GP-MXB, Pigel 10 μmMIXED-B GPC/SEC Columns, Fa. Agilent Technologies (eigentlicherHersteller ist auch Polymer Laboratories) GPC Standards: EasiCal PS-1Polystyrene Standards, Spatula A+B (Styrene Standard ManufacturerPolymer Laboratories (Now entity of Varian, Inc.; Varian DeutschlandGmbH; http://www.polymerlabs.com)

Mooney Viscosity ML1+4 (100° C.)

Mooney viscosity was measured according to ASTM D 1646 (2004), with apreheating time of one minute and a rotor operation time of 4 minutes,at a temperature of 100° C. [ML1+4 (100° C.)], on a MV 2000E from AlphaTechnologies UK. The rubber Mooney viscosity measurement is performed ondry (solvent free) raw polymer (unvulcanized rubber). The Compound Moonyviscosity is measured on an uncured (unvulcanized) second state polymercompound sample prepared according to Tables 4, 5 and 6. The CompoundMooney values are listed in Tables 8 and 10.

Vulcanizate Compound Properties

Tensile Strength, Elongation at Break and Modulus at 300% Elongation(Modulus 300) were measured according to ASTM D 412-98A (reapproved2002), using a dumbell die C test pieces on a Zwick Z010. Of thestandardized dumbbell die C test pieces, those of “2 mm thickness” wereused. The tensile strength measurement was performed at roomtemperature, on a cured (vulcanized) second stage polymer sample,prepared according to Tables 4, 5 and 6. Stage 2 formulations werevulcanized within 20 minutes at 160° C. to TC 95 (95% vulcanizationconversion).

Heat build up was measured according to ASTM D 623, method A, on a Doli‘Goodrich’-Flexometer. The heat built up measurement was performed onvulcanized second stage polymer samples.

Tan δ at 60° C. and Tan δ at 0° C., as well as Tan δ at −10° C.measurements, were performed on cylindrical specimen, using a dynamicmechanical thermal spectrometer “Eplexor 150N,” manufactured by GaboQualimeter Testanlagen GmbH (Germany), by applying a compression dynamicstrain of 0.2%, at a frequency of 2 Hz, at the respective temperatures.The smaller the index at a temperature of 60° C., the lower is therolling resistance. Tan δ (0° C.) was measured using the same equipmentand load conditions at 0° C. The larger the index at this temperature,the better the wet skid resistance. Tan δ at 60° C. and Tan δ at 0° C.,as well as Tan δ at −10° C. were determined (see Tables 9 and 11).

DIN abrasion was measured according to DIN 53516 (1987-06-01). Thelarger the index, the lower the wear resistance. The abrasionmeasurement was performed on a vulcanized, second stage polymerformulation. In general, the higher the values for Elongation at Break,Tensile Strength, Modulus 300, and Tan δ at 0° C., the better the sampleperformance; whereas the lower the Tan δ at 60° C., Heat Build Up, andAbrasion, the better the sample performance.

Examples 1 to 3—Batch Polymerisation/In Situ Formation of Catalyst

4000 g Cyclohexane and 1,3-butadiene (see table 1 for amount of1,3-butadiene) were placed in a 20 l polymerization pressure reactor(available from Karl Kurt Juchheim Laborgeräte GmbH, 1997 model, fabric.No. 2245) under nitrogen at 20° C. before adding di-iso-butyl aluminumhydride (DiBAH; 0.25 molar solution in Cyclohexane) and diethylaluminumchloride (DEAC; 0.1 molar solution in cyclohexane) in the amountsspecified in table 1.

360 g cyclohexane was placed in a second pressure vessel under nitrogen(1 to 2 liter pressure reaction vessel available from Büchiglasuster,fabric. No. 3618, model 2002) and cooled to 10° C. before 8 g DiBAH(0.25 molar solution in cyclohexane), Neodymium(versatate)₃ (0.029 molarin cyclohexane; NdV40@ purchased from Rhodia; see “rare earth elementcompound” in table 1 for amount) and 1,3-butadiene (molar ratio ofbutadiene to Nd=12) were added.

Polymerization was started by adding the content of the second vessel tothe polymerization reactor. The temperature was adjusted to 65° C. androse up to 80° C. within 30 min. Monomer conversion was monitored usinga halogen moisture Analyzer HR 73 (Mettler Toledo) by weighing 3 to 4 gpolymer solution into 50 ml Ethanol, filtering and transferring theprecipitate to the sample holder of the moisture analyzer and drying at140° C. for 5 to 10 minutes until weight remains constant. Conversion iscalculated as: conversion %=[weight (dired polymer sample)*(total weightof reaction mixture)*100]/[weight (sample of polymer solution)*totalweight of monomers]. Once 98% butadiene conversion was reached, asolution of alkoxysilane (1 weight percent in cyclohexane) was added(see table 1 for amount and silane). The reaction mixture was stirredfor another 15 minutes before a solution of disulfur dichloride (0.1weight percent in cyclohexane) was added in the amount specified intable 1.

The resulting polymer solution was stirred for 30 minutes before it wasstripped with steam for one hour to remove solvent and other volatilesand dried in an oven at 70° C. for 30 minutes and another one to threedays at room temperature.

Examples 4 to 6, 8 to 10—Continuous Polymerisation/Preformed Catalyst

Examples 4 to 6 and 8 to 10 were performed by means of three continuousstirred tank reactors (CSTRs) connected in series. Each reactor had avolume of 5 liter and was equipped with a helicoidal stirrer, suitablefor mixing high viscous solutions, the speed of the stirrer during alltrials was 200 rpm. External water circulation in the reactor wallsregulated the temperature of all three reactors to 80° C.

The reagents required for polymerization, i.e. the preformed catalyst(COMCAT Nd8.8; available from COMAR Chemicals Ltd.; applied as solutionof 0.022 mol Nd per kg cyclohexane solution) and 1,3-butadiene (seetable 1 for amount) as well as cyclohexane were continuously fed intothe head of the first reactor with mass flow-meters. Each flow-meterregulated the desired feed, and guaranteed a constant flow of thereagent. The flow of the preformed catalyst was 0.68 to 0.69 mmol/hbased on Nd (see “rare earth element compound” in table 1 for exactamount), the values indicated in table 1 are calculated based on theproduct specification available from COMAR Chemicals Ltd. taking thisflow into account. The flow of butadiene is indicated in table 1. Theflow of cyclohexane was adjusted such that the total flow of reactantsand solvent was 2.500 g/h.

The flow of the total amount of 1,3-butadiene, catalyst solution andsolvent was adjusted in order to achieve a residence time of 115 minutesin each reactor. The conversion after the first reactor was >95%conversion (calculated as described above with respect to Example 1). Inthe second reactor, a solution of alkoxysilane (1 weight percent incyclohexane) was added to the polymer solution (see table 1 for amountand silane) followed by the addition of a solution of disulfurdichloride (0.1 weight percent in cyclohexane) through the inlet of thethird reactor see table 1 for amount).

The resulting polymer solution continuously collected and afterwardsstripped with steam for one hour to remove solvent and other volatilesand dried in an oven at 70° C. for 30 minutes and another one to threedays at room temperature.

Example 7—Batch Polymerisation/Preformed Catalyst

4000 g Cyclohexane and 1,3-butadiene (see table 1 for amount of1,3-butadiene) were placed in a 20 l polymerization pressure reactor(available from Karl Kurt Juchheim Laborgeräte GmbH, 1997 model, fabric.No. 2245) under nitrogen at 20° C. Polymerization was started by addinga solution of a preformed catalyst containing 0.89 mmol based on Nd(COMCAT Nd8.8; available from COMAR Chemicals Ltd.; applied as solutionof 0.022 mol Nd per kg cyclohexane solution; amount as indicated intable 1—see “rare earth element compound”; the values for DEAC/EASC andDiBAH are estimated based on the product specification available fromCOMAR Chemicals Ltd.) to the polymerization reactor. The temperature wasadjusted to 65° C. and rose up to 80° C. within 20 minutes. Monomerconversion was monitored as described above for Example 1. Once 98%Butadiene conversion was reached, 3.5 mmol “alkoxysilane compound SS”(see below for preparation of alkoxysilane compound SS) was added. Thereaction mixture was stirred for another 15 minutes before adding 1 mmoldisulfur dichloride.

The resulting polymer solution was stirred for 30 minutes before it wasstripped with steam for one hour to remove solvent and other volatilesand dried in an oven at 70° C. for 30 minutes and another one to threedays at room temperature.

Preparation of Alkoxysilane Compound SS

Alkoxysilane Compound SS is represented by Formula SS below, and can beprepared as follows by preparation pathway 1 or 2.

Preparation Pathway 1 (SS):

To a 100 mL Schlenk flask was charged 25 ml tetrahydrofuran (THF), 79.5mg (10 mmol) lithium hydride, and subsequently, 1.96 g (10 mmol)gamma-mercaptopropyl trimethoxy silane [Silquest A-189] from the CromtonGmbH. The reaction mixture was stirred for 24 hours at 20 to 25° C., andanother two hours at 50° C. Then, tert-butyl dimethyl chloro silane(1.51 g (10 mmol)) was dissolved in 10 g THF, and the resulting solutionwas added drop wise to the Schlenk flask. Lithium chloride precipitated.The suspension was stirred for about 24 hours at room temperature, andfor another two hours at 50° C. The THF solvent was removed under vacuumbefore cyclohexane (30 ml) was added to yield a white precipitate. Thewhite precipitate was subsequently separated by filtration. Thecyclohexane solvent was removed under vacuum (reduced pressure). Theresulting colorless liquid proved to be alkoxysilane compound SS in 99%purity (GC), and therefore no further purification was necessary. Ayield of 2.9 g (9.2 mmol) of modified coupling agent (SS) was obtained.

Preparation Pathway 2 (SS):

To a 100 mL Schlenk flask was charged 1.96 g (10 mmol)gamma-mercaptopropyl trimethoxy silane [Silquest A-189] from CromtonGmbH, 25 ml tetrahydrofuran (THF), and subsequently, 0.594 g (11 mmol)sodium methanolate (NaOMe) dissolved in 10 mL THF. The reaction mixturewas stirred for 18 hours at 20 to 25° C. Then, tert-butyl dimethylchloro silane (1.51 g (10 mmol)) was dissolved in 10 g THF, and theresulting solution was added drop wise to the Schlenk flask. Sodiumchloride precipitated. The suspension was stirred for about 24 hours atroom temperature, and for another two hours at 50° C. The THF solventwas removed under vacuum before cyclohexane (30 ml) was added to yield awhite precipitate which was subsequently removed by filtration. Thecyclohexane solvent was removed under vacuum (reduced pressure). Theresulting colorless liquid solution proved to be alkoxysilane compoundSS in 89% purity (GC). After further purification by means offractionated distillation, a yield of 2.2 g (7.2 mmol) of alkoxysilanecompound SS was obtained.

TABLE 1 polymerization alkoxy rare earth silane Thio element compoundcompound compound DEAC¹ DiBAH 1,3-butadiene (silane: (S2Cl2; Example(mmol) (mmol) (mmol) (mol) mmol) mmol) 1 1 2.5 12 12.37 0 0 2 1.05 2.5713.3 12.73 TMS: 2.5 4.46 3 1.13 2.51 12 12.7 HMDS: 3.22 1.6 4 0.68/h1.7-2/h 7-12/h 6.1/h TMS: 0.5/h 0.55/h 5 0.69/h 1.7-2/h 7-12/h 6.2/hTMS: 0.6/h 0.32/h; HMDS: 0.08/h 6 0.69/h 1.7-2/h 7-12/h 6.3/h HMDS:0.54/h  0.3/h 7 0.89 2.2-2.6 9-15 6.3 SS“:” 1 3.5 8 0.68/h 1.7-2/h7-12/h 6.2/h TMS: 0.5/h 0.6/h 9 0.68/h 1.7-2/h 7-12/h 6.1/h TMS: 0.5/h0.55/h 10 0.69/h 1.7-2/h 7-12/h 6.1/h HMDS: 0.4/h 0.3/h TMS =tetramethoxysilane HMDS = hexamethoxydisilane ¹instead of DEAC alone, amixture of diethyl aluminum chloride (DEAC) and ethyl aluminumsesquichloride (EASC) was used in examples 4 to 10 for catalystformation

The polymers obtained according to examples 1 to 10 were analyzed. Thecis-1,4 polybutadiene content was determined to be above 96% for eachpolymer, the trans-1,4 content was of from 1.5 to 2.5% for each polymer,and the vinyl content (1,2-polybutadiene unit content) was found to be 1mol % for each polymer. Further polymer characteristics are given inTable 2.

TABLE 2 Polymer Characteristics Polymer Solution Viscosity MooneyPolymer Mn^(A) Mw^(A) [cPoise at viscosity Example [g/mol] [g/mol]Mw/Mn^(A) shear-rate 16/s] [MU] 1 247223 853819 3.45 17500E 43.6 2185190 670038 3.63 20200D 45.5 3 211410 711052 3.36   n.d. ^(G) 47.6 4n.d. n.d. n.d. n.d. 41.8 5 217812 463498 2.13 n.d. 43.6 6 195969 4708502.40 n.d. 40.6 7 252037 571765 2.27 n.d. 46.6 8 181403 444036 2.4512200E 41.2 9 192888 453605 2.35 n.d. 41.8 10 194744 442152 2.27 n.d.40.0 CB25 ^(F) 273917 599730 2.19 24200D 46.0 D: measured at 19 wt.-%polymer concentration in cyclohexane at 70° C. using a RS600 rheometerinstrument from Thermo-Haake, Germany; E: measured at 19 wt.-% polymerconcentration in an equimolar mix of n-hexane and n-heptane at 45° C.using a RheolabQC instrument from Anton Paar. ^(F) CB25 is a high cisbutadiene rubber that is commercially available from Lanxess and isproduced using a neodymium catalyst and reacting the polymer chains withS2Cl2. ^(G) n.d.—not detected

Polymer Compositions Comprising a Filler

Polymer compositions were prepared by combining the polymers obtained inexamples 1 to 10 above or commercially available polymer CB25 with theconstituents listed below in Table 4 (for polymers obtained in examples1, 2 and 3), Table 5 (for polymers obtained in examples 4, 5, 6 and 7 orCB25) and Table 6 (for polymers obtained in examples 5, 8, 9 and 10 orCB25), in a “380 cc Banbury mixer (Labstation 350S from BrabenderGmbH&Co KG),” following a two-stage mixing process. Stage 1: allcomponents as indicated in tables 4 or 5 were mixed together for 7minutes at 70 to 80 rpm, except for the components of the vulcanizingagent (i.e. sulfur, TBBS, and DPG) to form a stage 1 formulation. Stage2: Subsequently, the vulcanizing agent was added and the mixture wasmixed for additional 3 minutes at 40 rpm to give stage 2 formulations.Corresponding values for stage 1 and stage 2 formulations obtained fromthe components identified in table 6 are: 6 minutes at 90 rpm (stage 1)and 3 minutes at 50 rpm (stage 2), respectively. Mooney values weredetermined for each of these compositions (“stage 2 formulation”) andare indicated in tables 8 and 10 below as “Compound Mooney” values.Values for the compositions addressed in tables 4 and 6 were eachdetermined after sample preparation by the same operator on the sameday. Likewise, Compound Mooney values for composition 4 and 5 (table 5)were determined after sample preparation by the same operator on oneday, and Compound Mooney values for compositions 6, 7 and CB25 were alsodetermined after sample preparation by the same operator on the sameday. After preparation of stage 2 formulations, vulcanization wasstarted by heating the stage 2 formulations at 160° C. for 20 minutes.

TABLE 4 Polymer Compositions 1, 2 and 3 using polymers obtained inexamples 1, 2 and 3, respectively Amount Components (phr)^(n) SSBR(solution made styrene VSL5025-OHM^(m) 60.0 butadiene copolymer) Polymer1, 2 or 3 40.0 (High cis-polybutadiene) Precipitated silica Ultrasil7000GR^(f) 80.0 Silane NXT^(f,i) 9.7 Stearic acid^(j) 1.0 Stabilizersystem: Ozone protecting wax Antilux 654^(h) 1.5 AntiozonantDusantox^(g) 6PPD 2.0 Zinc oxide^(k) 2.5 Softener (Oil) TDAE^(e) 20.0Sulfur^(d,l) 1.4 TBBS^(b,d) 1.5 DPG^(c,d) 1.5 a 2 stage mixing,Brabender 350S, Internal Banbury mixer^(b)N-t-butyl-2-benzothiazolsulfenamide, Santocure-TBBS, Flexsys Inc.^(c)Diphenylguanidine, Vulkacit D, Lanxess AG ^(d)Second stage (curingsystem) e VivaTec 500, Hansen & Rosenthal KG ^(f)Evonic AG^(g)N-(1,3-dimethylbutyl)-N′-phenyl-1,4-benzenediamine, Duslo a.s.^(h)Light & ozone protective wax, Rhein Chemie Rheinau GmbH i Momentive^(j)Cognis GmbH ^(k)Grillo-Zinkoxid GmbH ^(l)Solvay AG ^(m)Lanxess AG^(n)Based on sum weight of the styrene butadiene copolymer andelastomeric diene polymer

TABLE 5 Polymer Compositions 4, 5, 6, 7 and CB25_silica using polymersobtained in examples 4, 5, 6 and 7 or CB25, respectively AmountComponents (phr)^(n) SSBR (solution made styrene ZA28-X1Sprintan(R) 60.0butadiene copolymer) SLR-4602 - Schkopau^(m) Polymer 4, 5, 6, 7 or CB2540.0 (High cis-polybutadiene) Precipitated silica Ultrasil 7000GR^(f)80.0 Silane Si 75^(f,i) 6.9 Stearic acid^(j) 1.0 Stabilizer system:Ozone protecting wax Antilux 654^(h) 1.5 Antiozonant Dusantox^(g) 6PPD2.0 Zinc oxide^(k) 2.5 Softener (Oil) TDAE^(e) 20.0 Sulfur^(d,l) 1.4TBBS^(b,d) 1.5 DPG^(c,d) 1.5 a 2 stage mixing, Brabender 350S, InternalBanbury mixer ^(b)N-t-butyl-2-benzothiazolsulfenamide, Santocure-TBBS,Flexsys Inc. ^(c)Diphenylguanidine, Vulkacit D, Lanxess AG ^(d)Secondstage (curing system) e VivaTec 500, Hansen & Rosenthal KG ^(f)Evonic AG^(g)N-(1,3-dimethylbutyl)-N′-phenyl-1,4-benzenediamine, Duslo a.s.^(h)Light & ozone protective wax, Rhein Chemie Rheinau GmbH^(i)Bis(triethoxysilylpropyl)disulfan, sulfur equivalents per molecule:2.35 ^(j)Cognis GmbH ^(k)Grillo-Zinkoxid GmbH ^(l)Solvay AG ^(m)StyronDeutschland GmbH ^(n)Based on sum weight of the styrene butadienecopolymer and elastomeric diene polymer

TABLE 6 Polymer Compositions 5A, 8, 9, 10 and CB25_carbon black usingpolymers obtained in examples 5, 8, 9 and 10 or CB25, respectivelyAmount Components (phr)^(h) Polymer 5, 8, 9, 10 or CB25 100 (Highcis-polybutadiene) IRB 7 international ref. 50 carbon black, SidRichardson Stearic acid^(e) 1.5 Zinc oxide^(f) 3.0 Softener (AromaticOil) TDAE^(d) 5.0 Sulfur^(c,g) 1.75 TBBS^(c,d) 1.0 a 2 stage mixing,Brabender 350S, Internal Banbury mixer bN-t-butyl-2-benzothiazolsulfenamide, Santocure-TBBS, Flexsys Inc.^(c)Second stage (curing system) ^(d)VivaTec 500, Hansen & Rosenthal KG^(e)Cognis GmbH ^(f)Grillo-Zinkoxid GmbH ^(g)Solvay AG ^(h)Based onweight of the elastomeric diene polymer

The compositions thus prepared were evaluated after vulcanization togive properties as disclosed in tables 9 and 11.

TABLE 8 Compound Mooney of Polymer compositions (“stage 2 formulations”)Compound Compound Polymer Mooney Mooney − Mooney Composition [Mu]Polymer 1 54.2 10.6 2 47.6 2.1 3 47.5 −0.1 4 51.2 9.4 5 74.6 31.0 6 78.938.3 7 91.2 44.6 CB25 95.3 49.3

TABLE 9 Silica Containing Polymer Vulcanizate Composition Properties(“Stage 2 formulations” after vulcanization) DIN Abrasion 0.5 kgElongation Tensile Modulus Tan δ Tan δ load at Break Strength 300 at atTan δ Example [mm] [%] [MPa] [MPa] −10° C. 0° C. at 60° C. 4 86 410 17.811.0 0.286 0.229 0.107 5 80 409 17.4 10.9 0.279 0.228 0.114 6 95 44918.2 10.1 0.287 0.232 0.117 7 82 436 18.6 10.9 0.263 0.221 0.112 CB25 95400 18.2 11.1 0.255 0.225 0.116

TABLE 10 Compound Mooney of Polymer Compositions (“Stage 2Formulations”) Compound Compound Polymer Mooney Mooney − MooneyComposition [Mu] Polymer 5A 65.2 21.6 CB25_carbon 73.9 28.1 black 8 62.521.3 9 62.5 20.7 10 61.6 21.6

TABLE 11 Carbon Black Containing Polymer Vulcanizate CompositionProperties (“Stage 2 formulations” after vulcanization) DIN Abrasion 0.5kg Elongation Tensile Modulus Tan δ load at Break Strength 300 at Tan δat Tan δ at Example [mm] [%] [MPa] [MPa] −10° C. 0° C. 60° C. 5A 20 47717.7 9.5 0.149 0.142 0.117 CB25_Carbon 20 470 19.8 11.1 0.139 0.1330.112 black 8 20 453 16.9 9.7 0.148 0.141 0.120 9 20 415 15.5 10.0 0.1470.142 0.118 10  19 468 17.1 9.6 0.151 0.146 0.121

Polymer compositions 2 and 3 show lower Compound Mooney values ascompared to polymer composition 1 (table 8). Since the mooney viscosityvalues of the corresponding polymers that were used for the preparationof polymer compositions 1, 2 and 3 are similar (see table 2), thedifference of “Compound Mooney” (indicated in Table 8) and “MooneyPolymer” (indicated as Mooney viscosity [MU] in table 2), i.e. “CompoundMooney—Mooney Polymer” (herein also referred to as “delta Mooney”) islower for polymer compositions 2 and 3 as compared to polymercomposition 1 that makes use of the linear, non-branched referencepolymer 1.

Likewise, table 8 reveals lower delta Mooney values for polymercompositions 4, 5, 6 and 7 as compared to comparative composition CB25.At the same time, the examples according to the invention showcomparable or even better vulcanizate composition properties asexpressed in table 9.

Similarly, carbon black containing polymer compositions 5A, 8, 9 and 10show lower delta Mooney values as compared to reference compositionCB25_Carbon black (table 10), and vulcanizate composition propertieswere again found to be comparable or better for the examples accordingto the invention (table 11).

The process of the invention yields polymers with improved processingproperties. Without wishing to be bound by theory, the inventors believethat the improved processing behavior is the result of a specificbranching between the polymer chains. The experiments show, that theunique polymer properties are the result of first adding one or morealkoxysilane compounds and then, subsequently, adding a thio compound tothe reaction mixture derived from process step i).

What is claimed is:
 1. A diene polymer prepared by a process,comprising: i) polymerizing one or more diene monomers in the presenceof a catalyst composition to give a reaction mixture; wherein thecatalyst composition comprises one or more of a carboxylate, an alkylphosphate, an alkyl phosphite, an alcoholate, an amide and a hydrocarbylcompound of a rare earth element having an atomic number of 57 to 71 inthe periodic table, and at least one activator compound, or a reactionproduct of the at least one activator compound and the carboxylate,alkyl phosphate, alkyl phosphite, alcoholate, amide and/or hydrocarbylcompound of the rare earth element; ii) adding to the reaction mixtureone or more alkoxysilane compounds selected from the compoundsrepresented by the following formulae (A1), (A2), (A3), (A4) and (A5):((R¹O)_(q)(R²)_(r)Si)_(s)  (A1) wherein in formula (A1): Si is siliconand O is oxygen; s is an integer selected from 1 and 2; with the provisothat if s is 1, then q is an integer selected from 2, 3 and 4; r is aninteger selected from 0, 1 and 2; and q+r=4; and if s is 2, then q is aninteger selected from 1, 2 and 3; r is an integer selected from 0, 1 and2; and q+r=3;((R³O)_(t)(R⁴)_(u)Si)₂O  (A2) wherein in formula (A2): Si and O are asdefined above; t is an integer selected from 1, 2 and 3; u is an integerselected from 0, 1 and 2; and t+u=3;(R⁵O)_(w)(R⁶)_(x)Si—R⁷—S—SiR⁸ ₃  (A3) wherein in formula (A3): Si and Oare as defined above, and S is sulfur; w is an integer selected from 2and 3; x is an integer selected from 0 and 1; and w+x=3;(R⁹O)_(y)(R¹⁰)_(z)Si—R¹¹—N(SiR¹² ₃)₂  (A4) wherein in formula (A4): Siand O are as defined above, and N is nitrogen; y is an integer selectedfrom 2 and 3; z is an integer selected from 0 and 1; and y+z=3;(Si(OR¹³)₃)₂(Si(OR¹⁴)₂)_(p)  (A5) wherein in formula (A5): Si and O areas defined above; p is an integer selected from 1 to 10; and wherein R¹,R², R³, R⁴, R⁵, R⁶, R⁸, R⁹, R¹⁰, R¹², R¹³ and R¹⁴ in the above formulae(A1) to (A5) independently are selected from: (C₆-C₂₁) aryl, (C₇-C₂₂)alkylaryl and (C₁-C₁₆) alkyl; and R⁷ and R¹¹ in formulae (A3) and (A4)independently are a divalent (C₆-C₂₁) aryl group, a divalent (C₇-C₂₂)alkylaryl group, or a divalent (C₁-C₁₆) alkylene group; iii) addingS₂Cl₂, SCl₂, S₂Br₂, SOBr₂ or a mixture thereof to the reaction mixture;and iv) optionally adding a protic agent to the reaction mixture so asto deactivate the catalyst.
 2. The diene polymer of claim 1, furthercomprising a polydispersity (Mw/Mn) of from 1.0 to 3.0.
 3. A productcomprising the diene polymer of claim
 1. 4. The product of claim 3,wherein the product is a tire tread or a tire side wall.
 5. The dienepolymer of claim 1, wherein groups R¹, R², R³, R⁴, R⁵, R⁶, R⁸, R⁹, R¹⁰,R¹², R¹³ and R¹⁴ in formulae (A1) to (A5) are independently selectedfrom C₁₋₈ alkyl groups.
 6. The diene polymer of claim 1, wherein groupsR¹, R³, R⁵, R⁹, R¹³ and R¹⁴ in formulae (A1) to (A5) are independentlyselected from C₁₋₄ alkyl groups.
 7. The diene polymer of claim 1,wherein the rare earth element is selected from the group consisting oflanthanum, praseodymium, cerium, neodymium, gadolinium, dysprosium, andany combination thereof.
 8. The diene polymer of claim 1, wherein thecatalyst composition comprises a neodymium carboxylate.
 9. The dienepolymer of claim 1, wherein the activator compound comprisesdialkylaluminum hydride according to general formula (A6) and a Lewisacid:R¹⁵ ₂AlH  (A6) wherein both groups R¹⁵ in formula (A6) are independentlyselected from C₁₋₁₀ alkyl groups.
 10. The diene polymer of claim 9,wherein the Lewis acid is an alkyl aluminum chloride selected from alkylaluminum sesquichloride, dialkyl aluminum chloride and alkyl aluminumdichloride.
 11. The diene polymer of claim 1, wherein S₂Cl₂, SCl₂,S₂Br₂, SOBr₂ or the mixture thereof is added in an amount of less than0.05 parts by weight based on 100 parts by weight of diene polymer. 12.The diene polymer of claim 1, wherein the one or more alkoxysilanecompounds are selected from the compounds represented by formulae (A1),(A2), (A3) and (A4).
 13. The diene polymer of claim 1, wherein the oneor more alkoxysilane compounds are selected from the compoundsrepresented by formulae (A1) and (A3).
 14. The diene polymer of claim 1,wherein the one or more alkoxysilane compounds are selected from(CH₃O)₄Si, ((CH₃O)₃Si)₂ and (CH₃O)₃Si—(CH₂)₃—S—Si(CH₃)₂C(CH₃)₃.
 15. Acomposition comprising the diene polymer of claim 1 and a filler. 16.The composition of claim 15 wherein the filler comprises at least one ofcarbon black, silica, carbon-silica dual-phase filler, clay, layeredsilicates, calcium carbonate, magnesium carbonate, lignin, carbonnano-tubes, amorphous fillers, glass particle based fillers, starchbased fillers, or combinations.
 17. A composition comprising the dienepolymer of claim 1 and a solution made styrene butadiene copolymer(SSBR).
 18. A composition comprising the diene polymer of claim 1, aSSBR, and a filler.
 19. The composition of claim 18 wherein the fillercomprises at least one of carbon black, silica, carbon-silica dual-phasefiller, clay, layered silicates, calcium carbonate, magnesium carbonate,lignin, carbon nano-tubes, amorphous fillers, glass particle basedfillers, starch based fillers, or combinations.